Acetyl choline levels in the brain are known to be higher in animals that are awake than those who are sleeping. (see for example Saito et al Life Sci (Jan. 15, 1975, 16 (2): 281-8 and Zatz et al, Brain Res (May 11, 1981 212(1): 234-8). It has also been reported that when brain acetyl choline in rats was depleted their diurnal activity cycle was disrupted (Szymusia et al Brain Res Nov. 26, 1993 629 (10): 141-5. Furthermore chemicals that interfere with cholinesterase mechanisms are known to promote REM sleep over slow wave sleep (see for example a review by J. Valazquez--Moctezuma et al in S. M. Aquilonius and P. G. Gilberg (Eds) Progress in Brain Research, Vol. 84 1990 Elsevier Science Publishers 8V.. N.Y. pp. 407-413. Galanthamine is a known acetyl cholinesterase inhibitor. Such inhibitors act to reduce the rate at which acetyl choline is removed from a locus by the action of acetyl cholinesterase and thus may increase the local concentrations of acetyl choline in regions from which it would otherwise be removed by the cholinesterase. Galanthamine has been used for many years in eastern Europe as a recovery agent for use after anaesthesia and has recently been subject to clinical testing in Europe as a possible treatment for Alzheimer's Disease. (see also U.S. Pat. No. 4,663,318 B. Davis, May 5, 1987). Other recent suggestions for its use have been in connection with treatment of male erectile impotence (see U.S. Pat. No. 5,177,070 R. Katz Jan. 5, 1993) and in treatment of chronic fatigue syndrome (see U.S. Pat. No. 5,312,817 E. Snorrason, May 17, 1994).